"What is the most addictive drug?"-- This and other thoughts on defining addiction

Although the consequences of using and difficulty to rehabilitate from a substance depend on many factors, including frequency and amount of time of use, the drug of choice must be considered. Drugs of abuse include, but are not limited to, marijuana, cocaine, methamphetamine, MDMA (or ecstasy), so-called “club drugs” (GHB, Ketamine, and Rophynol), LSD, phencyclidine, mescaline, heroin, opium, inhalants, anabolic steroids, and prescription drugs such as benzodiazepines and opiates pain medications. According to a 1990-1992 study from the National Comorbidity Survey, it was estimated that among 15-54 year-olds, the most commonly abused illicit drug was marijuana, with 46.3% of individuals responding affirmatively when asked if they had ever used a given substance. However, among users of any given drug, the drug with the highest percentage of dependence among individuals was heroin, with 23.1% of users dependent on the substance.

Before being able to pin down addiction, as defined for a given illicit drug, it is important to define addiction. While individuals disagree about the exact meaning of “addiction” the DSM-IV-TR defines substance abuse, which is the precursor to any form of addiction, as:

A. A maladaptive pattern of substance use leading to clinically significant impairment or distress, as manifested by one (or more) of the following, occurring within a 12-month period:

1.     Recurrent substance use resulting in a failure to fulfill major role obligations at work, school, or home (e.g., repeated absences or poor work performance related to substance use; substance-related absences, suspensions or expulsions from school; neglect of children or household)

2.     Recurrent substance use in situations in which it is physically hazardous (e.g., driving an automobile or operating a machine when impaired by substance use)

3.     Recurrent substance-related legal problems (e.g., arrests for substance-related disorderly conduct

4.     Continued substance use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the substance (e.g., arguments with spouse about consequences of intoxication, physical fights)

B. The symptoms have never met the criteria for Substance

             Dependence for this class of substance.

Individual drug addictions, referred to by the DSM, as “dependence” are similar among various substance types despite small differences for a given drug. An example is seen in classification of opioid dependency:

            1. A strong desire or sense of compulsion to take the drug;

2. Difficulties in controlling drug-taking behavior in terms of its onset, termination, or levels of use;

3. A physiological withdrawal state when drug use is stopped or reduced, as evidenced by: the characteristic withdrawal syndrome for the substance; or use of the same (or a closely related) substance with the intention of relieving or avoiding withdrawal symptoms;

4. Evidence of tolerance, such that increased doses of the drug are required in order to achieve effects originally produced by lower doses;

5. Progressive neglect of alternative pleasures or interests because of drug use, increased amount of time necessary to obtain or take the drug or to recover from its effects;

6. Persisting with drug use despite clear evidence of overtly harmful consequences, such as harm to the liver, depressive mood states or impairment of cognitive functioning.

The DSM’s sixth point is important, especially for researchers who study drug addiction. Individuals who have a drug addiction are usually aware that their lifestyle choices have negative effects; however, their choice to use the drug despite such consequences is one of the primary characteristics of an addiction. What leads people to continue to intake substances that causes obvious self-harm?